1. Field of the Invention
The invention relates to an electro-acoustic transducer and an electronic device using the same, and more particularly, to a flexible luminescent electro-acoustic transducer and an electronic device using the same.
2. Description of the Related Art
Flexible luminescent boards can generate light due to possession of a phosphor material. When the phosphor material is driven by a high voltage, the energy levels of electrons inside the phosphor material will change to cause a fluorescent emission. Referring to FIG. 1, a conventional flexible luminescent board 100 includes a fluorescent layer 130 and a dielectric layer 140 positioned under the fluorescent layer 130. A rear electrode 150 is positioned under the dielectric layer 140 and a front transparent electrode 120 is positioned above the fluorescent layer 130. A front transparent protective cover 110 is positioned above the front transparent electrode 120 and a rear protective cover 160 is positioned under the rear electrode 150. In order to make the luminescent board 100 generate a fluorescent emission, it is necessary to apply an enough voltage to the electrodes 120 and 150. When a voltage is applied, an electric filed will be built up between the electrodes 120 and 150 accordingly. The electrons inside the fluorescent material of the fluorescent layer 130 can therefore acquire enough energy to make a transition from a low energy state to a high energy state. When the electrons return to the low energy state, they will generate fluorescent light accordingly. The light can travel through the front transparent electrode 120 and front protective cover 110 to leave the luminescent board 100. Although the above luminescent board 100 can generate a fluorescent emission, it is incapable of generating sound.
Piezoelectric loudspeakers or receivers are ones that have their diaphragms made of piezoelectric material. Alternatively, the diaphragms are formed by attaching the piezoelectric material to a flexible substrate. When an external electrical signal is applied to the piezoelectric sheet, the electrical signals will stimulate the piezoelectric material to cause a deformation. The deformation of the diaphragm induced by the piezoelectric material can push the air to make sound. Referring to FIG. 2, it illustrates a conventional piezoelectric loudspeaker 200. An electrode 220 is positioned on the flexible substrate 210 of the loudspeaker 200 and a piezoelectric layer 230 is positioned on the electrode 220. A counter electrode 240 corresponding to the electrode 220 is positioned on the piezoelectric layer 230. When an electrical signal is applied to the electrodes 220, 240, the electrical signals will stimulate the piezoelectric layer 230 to cause a deformation. If the electrical signal applied to the electrodes 220, 240 alternately changes, the piezoelectric layer 230 and substrate 210 will be induced to vibrate to make sound. Although the above loudspeaker 200 can generate sound, it is incapable of generating light.
The above luminescent board and loudspeaker are independent to each other. It is required to provide individual space for each element when these elements are equipped to a same device.
Accordingly, there exists a need to provide a device with the function of making sound and generating light to solve the above-mentioned problems.